1. Field of the Invention
The present invention relates to techniques, both method and apparatus, for reducing graphic patterns which are coded by binary characters and which are displayed in rows and columns of a prescribed grid.
2. Description of the Prior Art
The telecommunication service "picture screen text" offers the possibility of displaying graphic patterns on the picture screen of a television set in addition to alphanumeric characters. The graphic patterns are composed of individual graphic elements. Each page of picture screen text which can be displayed on the screen comprises 80.times.72=5760 graphic elements given a graphics input. Six such graphic elements are respectively combined into a character field having a size of 2.times.3. Therefore, there derives 40.times.24=960 character fields per page. The graphic patterns can be displayed in eight colors, whereby only one color is possible within a character field. The coding of the graphic patterns occurs in the grid of the character fields.
A graphic pattern can be constructed by way of an editing keyboard. Thereby, the individual graphic elements are provided via corresponding keys. Within the prescribed grid, therefore, inputs at random positions are possible until the pattern to be displayed corresponds to the desired concepts. However, a display of extensive graphic patterns by employing the editing keyboard requires a significant expense with respect to time. It is further possible to input graphic patterns by scanning a corresponding master. The scanning can occur by employing a television camera or with the assistance of a scanner which scans the master line-by-line. Advantageously, the masters are already displayed in the grid formed of the graphic elements. After scanning, the binary characters assigned to the lines of the graphic master are usually stored in a primary memory for further processing.
In case a graphic pattern which is smaller than the graphic pattern illustrated on the master is desired for producing a page, it would be conceivable to produce a new master on which the graphic pattern is illustrated in the proper size and to then again scan this master. This technique, however, requires considerable expense. Further, it would be conceivable, when scanning the master with a television camera, to provide the television camera with a zoom lens and to change the focus in such a manner that the master is imaged in the television camera with a suitable size. Such a method, however, requires a mechanical adjustment of the lens.